Biochemical Properties of the Ovarian Granulosa Cell Type 2-Angiotensin II Receptor*

Abstract

Angiotensin II (Ang II) receptors, estimated by the specific binding of the peptide Ang II receptor antagonist [125I] [Sar1,Ile8]Ang II, are localized on multiple ovarian structures, including follicular granulosa cells. Using the Ang II receptor subtype-selective nonpeptide antagonists, DuP 753 [selective for the type 1 Ang II (AT1) receptor] and PD 123319 [selective for the type 2 Ang II (AT2) receptor], we show that follicular granulosa cells, in vivo and in vitro, exclusively express the AT2 receptor. To understand the function of Ang II in ovarian follicles, we compared the biochemical properties and transmembrane signaling pathways of the granulosa cell AT2 receptor with those properties generally associated with Ang II receptors found in the adrenal zona glomerulosa, where the AT1 receptor predominates. The mol wt of the granulosa cell AT2 receptor (approximately 79,000), estimated by affinity cross-linking studies, is similar to that of the adrenal zona glomerulosa Ang II receptor. Like the adrenal zona glomerulosa Ang II receptor, binding inhibition studies show that the granulosa cell AT2 receptor binds Ang II and Ang III with high affinity (IC50, approximately 0.5 nM for both peptides), but not Ang-(1-7) (IC50, approximately 0.5 microM) or Ang-(1-5) (IC50, greater than 10 microM). However, unlike the adrenal zona glomerulosa Ang II receptor, the granulosa cell AT2 receptor does not undergo agonist-induced endocytosis. Further, Ang II does not affect basal or stimulated inositol phosphate production, intracellular Ca2+ mobilization, or adenylyl cyclase or guanylyl cyclase activity in granulosa cells. The granulosa cell AT2 receptor does not appear to directly interact with guanine nucleotide binding regulatory proteins, since agonist dissociation from the AT2 receptor is unaffected by the GTP analog guanosine 5'-O-(3-thiotriphosphate); in contrast, the AT1 receptor appears to directly interact with guanine nucleotide binding regulatory protein, because agonist dissociation from the AT1 receptor is stimulated by guanosine 5'-O-(3-thiotriphosphate). These studies clearly demonstrate that the granulosa cell AT2 receptor is functionally distinct from the well characterized adrenal zona glomerulosa Ang II receptor. The exclusive presence of the AT2 receptor on the granulosa cell makes it an ideal cell type for studying the potential, but as yet unknown, function of this receptor.

The angiotensin type 2 receptor of angiotensin II and neuronal differentiation: from observations to mechanisms

“…Observations that in the fetus the AT 2 receptor is widely distributed in many brain structures and steroid-producing glands, such as the adrenal glands or the ovaries (Tanaka et al 1995, Breault et al 1996, Schutz et al 1996, Nuyt et al 1999, led to a hypothesis for a role in cellular differentiation. In the adult, AT 2 receptor expression is restricted to the uterus (Nielsen et al 1997), ovarian granulosa cells (Pucell et al 1991, Yoshimura et al 1996, Johnson et al 1997, adrenal glands (Belloni et al 1998, Wang et al 1998 and some areas of the brain involved in cognition and behavior (Song et al 1992, Lenkei et al 1996.…”

Interferon Regulatory Factor-1 Up-regulates Angiotensin II Type 2 Receptor and Induces Apoptosis

“…Interestingly, AT 2 receptor expression is tightly associated with ovarian follicular atresia (3,8). AT 2 receptor is also abundantly expressed in immature brain and some specific regions of the brain (5, 6).…”

“…Recently, a second receptor subtype known as AT 2 receptor has been cloned by us and others (1,2). The AT 2 receptor is abundantly and widely expressed in fetal tissues, but present only in at limited levels in adult tissues such as adrenal medulla, specific brain regions, uterine myometrium, heart, and atretic ovarian follicles (3)(4)(5)(6)(7)(8). The highly abundant expression of this receptor during embryonic and neonatal growth and quick disappearance after birth has led to the suggestion that this receptor is involved in growth, development, and/or differentiation.…”

Effect of A23187 or angiotensin II on ovarian metalloproteinase inhibitors and steroidogenesis in rats

“…(Rodland et al, 1992 (Werb and Burleigh, 1974) and rat uterus (Woessner and Ryan, 1973 (Zhu and Woessner, 1991) or from compartmentalization of the enzyme to the apex and the inhibitors to different compartments such as the granulosa cell layer (Mann et al, 1991 (Wan et al, 1996), or that there are divergent effects of calcium depending upon the intracellular concentration as previously reported for inositol phosphate (Bezprozvanny et al, 1991). (Pucell et al, 1987(Pucell et al, , 1991 (Kuo et al, 1991;Yoshimura et al, 1992Yoshimura et al, , 1994Yoshimura et al, , 1996bPeterson et al, 1993a). In loto, these findings suggest that All plays a role in follicular rupture.…”

“…In rats, stimulated oestradiol production by ovaries from PMSG-treated animals that had been sectioned into quar¬ ters (Pucell et al, 1987). In contrast, All had no effect on basal or FSH-stimulated aromatase activity in granulosa cells from diethylstilboestrol (DES)-primed rats but had a mild stimulatory effect on progesterone (Pucell et al, 1988(Pucell et al, , 1991. Progesterone production was also stimulated by All in luteinized rat granu¬ losa cell cultures (Lightman et al, 1989).…”